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23935•. I GEOTECHNICAL INVESTIGATION PROPOSED RESIDENTIAL DEVELOPMENT TENTATIVE TRACT 23935, SOUTHWEST CORNER OF DUNE PALMS ROAD AND MILES AVENUE LA QUINTA, CALIFORNIA LEIGHTON AND ASSOCIATES Geotechnical and Environmental Engineering Consultants Lf/GHTON AND ASSOCIATES, INC. Geotechnical and Environmental Engineering Consultants December 14, 1988 Project No. 5881448-01 TO: La Quinta 47 74-075'E1 Paseo, No. A4 Palm Desert, California 92260 SUBJECT: Geotechnical Investigation, Proposed Residential Development, Tentative Tract 23935, Southwest Corner of Dune Palms Road and Miles Avenue, La Quinta, California Introduction is In accordance with your authorization we have conducted a geotechnical investiga- tion at the subject site. The scope of our work included (1) site reconnaissance; (2) excavation, logging, sampling and backfill of ten exploratory trenches up to 13 feet in depth; (3) percolation testing for retention basin design; (4) laboratory testing of geotechnical properties of representative soil samples; (5) geotechnical analysis of field and laboratory test data and (6) preparation of this report presenting our findings, conclusions and recommendations. Our present scope of work did not include any assessment of the possible presence of hazardous chemical materials at the site. The approximate location of the exploratory trenches is shown on the drawing titled "Location of Trenches and Percolation Tests". Tentative Tract Map No. 23935, prepared by Engineering Service Corporation, Palm Desert, California, dated September 12, 1988 was used as a base map for this investigation. • Accompanying Maps and Appendices Site Location Map - Page 2 Figure 1 - Location of Trenches and Percolation Tests - Rear of Text Appendix A - Sampling and Testing Procedures Appendix B - Geotechnical Trench Logs Appendix C - Percolation Test Results Appendix D - Laboratory Test Results Appendix E - General Earthwork and Grading Specifications Appendix F - References 74-240 HIGHWAY 111, PALM DESERT, CALIFORNIA 92260 (619) 568-0993 FAX (619) 341-1490 tj i kJ • J --z. �.// � ` . , -- 11 • ��. ti, AVENUC 44• m TO �~\ Siphon Trailer tl : \ 20 B' Well 'f urtEs �'lE.V L'E -•:•i - 'AVENUE ParK•+' �.9 SITE_. GO Happy _Z) AVEIIUE 46 x • � � p,. .. •.�.;:' :4• � n res-- _aa -� ^� ..... .... ..:- { A . •_: % awn •� I _ �� y� .. �• •� yv `QC 4 warier- �:. r •• �.� r Pa7k/ hil • ill _ r 'i' � �� — BM 72.1 e •_' _ 1I120 BM..�t- •`� :E 2G° 111 (74 '75 1 30 - -S _ ,r— ..� —Trailer l- R..—�- n n t• a „ Ire n F _ � •.•_•_•. �.. _ +varier Park+J' r,• e . • .e Trailer •, Par I, 1• n n .. v� r .. •n ° 1711 Wel[ -- - - •L1-••—,. wVENUE48 .. W r•11:1 BASE MAP: USGS 7-1/.2' QUADRANGLE ::ti•:: "LA QUINTA, CALIFORNIA" Photorevised 1980 PROPOSED RESIDENTIAL DEVELOPMENT TENTATIVE TRACT 23935, SOUTHWEST CORNER OF DUNE PALMS ROAD AND MILES AVENUE, LA QUINTA, CALIFORNIA 00 2000 4000 scale feet SITE LOCATION MAP Project No. 5881448-01 - 2 - s 5881448-01 SITE CONDITIONS AND PROPOSED DEVELOPMENT • Site Conditions The approximately 50 acree site is located on the soutwest corner of Miles Avenue at Dune Palms Road. It is bordered on the west by vacant, undeveloped land, and to the south by a citrus orchard. Between the orchard and the site is a row of large tamarisk trees. At present, the site appears to be in a natural condition. Vegetation at the site consists of a sparse cover of creosote bush and desert grasses. The soils exposed at the surface consist of slightly silty fine grained sands. No structures, pavements or other evidence of previous development were observed at the site. Topographically, the site consists of northwest to southeast trending sand dunes. About 30 feet of vertical relief exists across the site, with the northeast corner relatively high and the southwest corner relatively low. Locally, the dunes reach a maximum height of about 20 feet relative to the adjacent trough areas. The existing slopes generally are flatter than 5:1 (horizontal :vertical) with oc- casional slopes as steep as 3:1. Proposed Development Based on Tentative Tract Map No. 23935, the proposed development will consist of 193 residential lots with the associated streets and utilities. Grading plans were not available at the time of this investigation, however, significant cut and fill grading is expected to be required to achieve the desired final grades. • Specific structural load information was not available, however, foundation loads are expected to be relatively light as is typical of most residential construc- tion. -3- LUGNTON AND ASSOCIATES, INC 5881448-01 FIELD AND LABORATORY INVESTIGATIONS Subsurface Investigation The su bsurf ace soi l s at the s i to were exams ned by means of ten backhoe trenches excavated to depths of up to 13 feet. The trenches were continuously logged by our field geologist, who collected representative samples of the soils encountered for further classification and testing. Sampling procedures are described in Appendix A. Approximate locations of the trenches are shown on Figure 1. Summaries of the trench logs are presented in Appendix B. Percolation Testin Test pits, three feet in depth, were excavated near trenches T-2 and T-7. At the bottom of each test pit, a 1 foot deep, 8 inch diameter test hole was dug by hand. The percolation tests were performed in the interval between 36 and 48 inches below the existing ground surface. Each test hole was lined with wire mesh wrapped with filter fabric. After a presoaking period, a one hour duration per- colation test was performed in each hole. The test hole was filled with water and at ten minute intervals during the hour, the water level was recorded and the hole refilled. Field data from the percolation tests are presented in Appendix C. The approximate locations of the percolation tests are shown on Figure 1. Laboratory Testing Samples of soils obtained from the exploratory trenches were returned to our laboratory for further testing. The in-place moisture content and density of the • soils are presented on the trench logs of Appendix B. Maximum density, sand equivalent, and gradation testing was performed on representative samples and the results are presented in Appendix D. -4- LEIGNTON AND ASSOCIATES, INC. • • CJ 5881448-01 Earth Materials • SUMMARY OF GEOTECHNICAL CONDITIONS The earth materials encountered during our site investigation consisted of wind blown deposits composed mainly of fine grained sand. In general, the soils in this area are gray in color, dry to slightly moist, and medium dense. Sieve analysis of two soil samples indicated from 2 to 12 percent passing the #200 sieve. Based on their classification, the onsite soils appear to be very low in expansion potential. The Sand Equivalent of three representative samples ranged f rom 49 to 61. Ground Water No free ground water or seepage was encountered in any of the trenches during our investigation. Based on information received from the Coachella Valley Water District, the regional ground water levels in the vicinity should be on the order of 90 feet or more below the ground surface. This water level may be expected to vary seasonally, but is not expected to impact construction at the site. Seismicity Regional geologic maps show that the nearest known active or potentially active faults to the site are the Mission Creek Fault and the Banning Fault, branches of the San Andreas Fault zone. These faults both trend northwest -southeast in the site area. The Banning Fault approaches within about 4-1/2 miles of the site and the Mission Creek Fault approaches within 5 miles of the site. Regional geologic and fault hazard maps show no faulting to be present at the site. The site is not included in the California Special Studies Zone. Liquefaction is a phenomenon involving total or substantial loss of shear strength in saturated soil. It is caused by the buildup of excess hydrostatic pressure in saturated cohesionless soils as a result of cyclic stresses generated by ground motions. The Riverside County Seismicity and Safety Element (1976) indicated the liquefaction potential at the site is minimal. Our investigation generally con- firms this finding due to the great depth to free ground water at the site. -5- LEIGHTON ANO ASSOCIATES, INC 5881448-01 • CONCLUSIONS AND RECOMMENDATIONS Conclusions Based on the results of our field exploration, laboratory testing and our ex- perience and judgment, in our opinion the site is suitable for the proposed development from a geotechnical standpoint. Some overexcavation, scarification, presoaking, and reworking of soils as compacted fill is recommended for areas to support structures or.pavements and to provide uniform foundation conditions, adequate bearing capacity and to minimize settlement. Excavations at the site may be accomplished with conventional earthmoving equipment. Some caving may be expected to occur in excavations at the site. Recommendations 1. Site Pre aration All grading should be performed in accordance with our General Earthwork Grading Specifications (Appendix D) except as modified in the text of this report. The site should be stripped of any trash, debris, vegetation, roots, undocu- mented fill soils and soft soils up to the required depth. During rough grading, excess soils may be stockpiled for later use. Soils containing more than one percent by weight of organics may be used in planter areas, but • should not be used for fill beneath building and paved areas. Debris and trash should be removed from the site. After clearing, the soils should be excavated to a minimum depth of 24 inches from existing ground or finish grade elevations, whichever is deeper. The exposed excavations should be further scarified, moisture conditioned to optimum moisture and recompacted to a minimum of 90 percent relative compaction to a depth of 6 inches prior to placement of fills. This overexcavation is intended to provide uniform support for structures and pavements. Additional excavation may be required in any areas to support structures or pavements where exceptionally soft, or loose soils are encountered. The excavations should extend a minimum of. 5 feet beyond the building footing lines or pavement limits. Building pads developed in cut areas should be similarly overexcavated below final pad grade. The soils in building pad areas should be checked for moisture penetration to depths of at least three feet below the depth of overexcava- tion. The trenches excavated for our subsurface exploration were up to 13 feet deep, approximately 15 feet long, and 3 feet wide. After logging and sam- pling, they were loosely backfilled. Where structures or pavements are planned at these locations, the trenches should be re -excavated to a depth of at least 36 inches below existing grade, as described above, scarified, heavily watered, recompacted, and backfilled with properly controlled com- pacted fill. -6- LEIGNTON AND ASSOCIATES, INC ' 5881448-01 • 2. Comoacted Fill • The onsite soils, free of organic material, are suitable for use as compacted fill. Imported fill should conform to the specifications in Appendix D. Any fill soils used should be moisture conditioned to near optimum moisture content and compacted to at least 90 percent relative compaction in accord- ance with ASTM D1557-18. Fill should generally be placed in uniform lifts not exceeding 8 inches (loose). 3. Shrinkaqe and Subsidence Based on test results, scarification and recompaction of the upper foundation soils should result in a shrinkage on the order of approximately 20 percent. This is based on an estimated average relative compaction of 92 percent. An increase in relative compaction obtained will correspondingly increase this shrinkage factor. A subsidence (due to equipment operations and prewatering) of approximately 0.30 feet is typically assumed in areas of sandy desert soils such as those at the subject site. 4. Foundation Design - Footings After site preparation as recommended, the use of shallow continuous footings or isolated spread footings is feasible. The footings for one-story or two-story wood frame residential structures should be 15 inches deep and at least 12 inches wide. A maximum allowable bearing value of 1800 psf is recommended for footings constructed in this manner. This value may be increased by one-third for wind or seismic loads. The footings may be rein- • forced with at least one No. 4 bar at the top and bottom to reduce the potential for cracking due to temperature and shrinkage stresses and a limited amount of hydroconsolidation. Adverse amounts of settlement may occur if the soils below the foundations become wetted after construction. It is therefore important to minimize the infiltration of water into the foundation soils. Positive drainage should be provided to direct surface water away from structures and slabs. Resistance to lateral loads can be developed by frictional resistance on the footing bottoms and passive pressure against footing sides. The frictional resistance can be computed using a frictional coefficient of 0.4. An allow- able passive earth pressure of 250 pounds per square foot per foot of depth may be used in calculating the resistance of dense natural soils or properly compacted fill to lateral forces. The maximum passive pressure should be limited to 2500 psf. The passive pressure should be neglected when computing lateral resistance unless the area adjacent to the foundations is confined by a slab or pavement. -1- ,rt LHO TON AND ASSOCIATES, INC 5881448-01 0 • 5. Surface Drainage and Lot Maintenance No water should be allowed to pond adjacent to the building. Positive • drainage may be accomplished by providing drainage away from the buildings at a gradient of at least 2 percent for a distance of at least 5 feet away from the building, and further maintained by a swale or drainage path at a gradient of at least 1 percent. Where necessary, drainage paths may be shortened by use of area drains and collector pipes. We suggest the instal- lation of eave gutters and downspouts on the buildings, which will facilitate roof runoff away from the foundation. The discharged water from the downspouts should be directed away from the buildings to an appropriate outlet. Some routine site maintenance should be expected to be required at intervals during the life of the structures. This may include maintaining grades to drain away from the structures, restoring soil removed from foundation areas by animal activity, wind or water erosion, etc. 6. Retention Basins Retention basins for infiltration of surface runoff water may be designed based on the percolation rates determined at the site. The minimum rate of approximately 0.7 minute per inch obtained in our field tests may be used for design when an appropriate factor of safety is applied. If the surface of the retention basins is to be planted with grass, or the soils in the reten- tion basin areas are reworked and compacted, the observed infiltration rate should be accordingly reduced or a larger factor of safety applied. 7. Concrete The slab subgrade and footing excavations should be properly moistened prior to placing of concrete. Concrete with low water:cement ratios and low slump (preferably 4 inches) when properly placed, vibrated, and cured will have a low potential for shrinkage cracking. 8. Slabs -on -Grade Slabs -on -grade should be at least 4 inches thick and should be reinforced in accordance with local codes and structural considerations. We suggest that slabs -on -grade be reinforced by either wire mesh (6 x 6 - 10/10 WWF) or #3 rebars at mi dhei ght in the slabs, spaced 18 inches on center in both direc- tions. irec- tions. We recommend that a moisture barrier consisting of a 6 -mil polyethylene sheet be placed beneath slabs in areas sensitive to moisture damage. The moisture barrier should have a 2 -inch layer of clean sand placed above it to aid in concrete curing. Openings in the vapor barrier should be carefully sealed and the vapor barrier should be carefully installed to avoid puncturing it and reducing its effectiveness. - 8 - 4 LEIGHTON AND ASSOCIATES, INC. 5881448-01 • 9. Asphaltic Concrete Pavement Based on their classification, we expect the R -value of the onsite soils to be on the order of 50 or more. Considering this and based on assumed traffic index values as indicated, recommended pavement sections are presented in the table below. A.C. with Base Course Full Depth A.C. A.C: base Course A.L. Assumed Thickness Thickness Thickness Service Conditions Traffic Index inches (inches) (inches) Light (Passenger car, parking areas) 4.0 2.0" 3.0" 4.0" Medium (Medium truck, service vehicles) 5.5 3.0" 4.0" 5.5" Asphaltic concrete should conform to Section 203 of the "Standard Specifications for Public Works Construction", (SSPWC). Base course should be a Crushed Aggregate Base or Processed Miscellaneous Base conforming to Sections 200-2.2 and 200-2.4 of the SSPWC. The base course and AC should be placed in accordance with Sections 301-2 and 302-5 of the SSPWC.. Concrete aprons or thickened asphalt pavement sections should be considered in areas where heavier loadings are likely, for instance, the areas in front of trash enclosures which are subject to heavy wheel loads imposed by trash removal vehicles. The upper 12 inches of subgrade materials below pavements should be compacted to 95 percent relative compaction. Our pavement evaluation was based on assumed traffic indices and the physical properties of the near -surface soils encountered on the project site. These recommendations should be reviewed if import soils are placed in the pavement areas or if the site conditions during construction appear to be different from those indicated by our trenches. If the traffic index values vary from the values given or import soils are placed in pavement subgrades, then this office should be notified so that pavement sections can be revised accord- ingly. 10. Seismic Considerations Seismic design considerations for structures in the southern California area are critical because of high regional seismic activity. Seismic design should be in accordance with the provisions of the current Uniform Building Code and the seismic design parameters of the Structural Engineers Association of California. `9- LEIGHTON AND ASSOCIATES, INC 5881448-01 • 11. Temporary Construction Excavations • The onsite soils are subject to caving. Particular attention should be given • to the possibility of caving along trench excavations. Laying back or shor- ing of deep utility excavations should, therefore, be a consideration. Temporary excavations during construction should be designed in accordance with the applicable safety codes. Sandy soils exposed in temporary construc- tion excavations should be kept moist but not saturated to retard ravelling and sloughing during construction. 12. Observation and Testing During Construction The recommendations provided in this report are based on preliminary design information and subsurface conditions obtained from the exploratory test pits at the site. Geotechnical observations and testing during construction are the continuation of this geotechnical investigation and not separate unique functions. Field review during site grading allows for evaluation of the exposed soil conditions and confirmation or revision of the assumptions and extrapolations made in formulating the design parameters and recommendations. If an engineering firm other than Leighton and Associates is contracted to act as soil engineer during later phases of this project, they should notify the owner, project designers, the appropriate regulatory agencies, and this office that they have assumed responsibility for all phases (design and construction) of the project within the purview of the geotechnical engineer. Notification should indicate they have reviewed this report and any sub- sequent addenda and either agree with the conclusions and recommendations or will provide new recommendations. Final project drawings should be reviewed by the geotechnical engineer prior to grading to see that the recommendations provided in this report are incorporated in the project plan. Construction should be observed by the geotechnical engineer at the following stages: i Upon completion of clearing and during excavation of building and pavement areas. During all stages of grading and earthwork operations including scarifica- tion, recompaction, and while utility trench backfilling. • Prior to paving or other construction over fill or backfill. • When any unusual soil conditions are encountered during construction. - 10 - LEIGHTON AND ASSOCIATES, INC. 5881448-01 A final report should be prepared upon completion of the construction, sum- marizing the compliance with the recommendations of this report and geotechnical observations during the grading work. If conditions during construction appear to be different from those indicated in this report, this office should be notified. If you have any questions regarding our report, please do not hesitate to contact this office. We appreciate this opportunity to be of service. DG/BJI/mu Distribution: (6) Addressee Respectfully submitted, LEIGHTON AND ASSOCIATES, INC. David Goodrich Staff Geologist Brent J. Inghram, RCE 40264 Chief Engineer Q�iJF ESS16,��` 4 BR NWT J. y INGRAM � W No. 4L764 CP CIVIL ��- qrE OF C ,0 � 5x14 �r }' �... MILES AVENUE Jr ....................... . ......... - 73 7! 57 41 40 25 14 _• 9 -8 74 'r 1,� I' 'f 5� 42 •y'1 29 16 .,LC4_ 7 s 75� 70 59 . -S 43 1 - - 27 L� ?2:' t 11 1 _ 76 I �69 60y d4 21S 37'.. .12 5 I 77 68 61 3 ~' S2 45 E . S 36 29 �0 ysl I St 46 1 .35 30- , _ t� I9 - .a � �w 't 379 50 1 721 • Lr..-�•L_��� � Q • _ .. HO--_ {� � ;� • .;� 6d - � • . � � � � 48 . � S ". 33• • • : j2 _ /� 17 � E so • 1. '� • Ka» w ',u t Z !34 '83 18? _Jf 180. I 139 D8 ` 119 118 83 :\�• 19T 2. $5y T7 178 r y =-�1 �. t7§ 176 `177 �-•--` - �— '.121 „ ^ l 135 " Ly 187 in 's 85' . ,`- --�-s i • 174-1123 . 171 ,•--- 1 - IZ2 ll�i jI{. - - 189 788 171 x 1171 86 {t.� ' + M`t 114 - R 1 '�..ti-.. •�- - yL:. '...`:-'M1y Eu�hL:�'r�•' �. r,.3 1'-.0 165. 166 161•- I'6d 162 125' L • ; +� a �, .. � � �".' r --- :� 1: 162 '� L58 �� 157 152 1 +'• i - }- 1' TREEr: 156 46 {`--• ~ ` 89.r 'i=ii •� ` -ia 65--riw - . - + x•453 ; . �v'" - •_ A >: p 149 148 �. � 154 M 78 .129 - � :'ii$ , 7� : - I •� • _ ^[ l \ -;�•1 - ` .,�5� =�'• 6 3••t�� _ -.ter _•� •ti•_� '_t •:'tX•''1�• �.� :QLr,^ �F:L}-c't'�+ry::'".L' _ .a'•7 -r LOCATION OF TRENCHES, AND PERCOLATION TESTS I H I - „I VICINITY MAP NO SCALE 20 2Q p i TYPICAL SECTION - INTERIOR STREETS r SLY E ee' R/1. 26_ I EXISTOG ` PAVEUENT EM totasea W40 • i TYPICAL SECTION - MILES AVENUE W VT *, 4,r t E.W T TYPICAL SECTION - DUNE PALMS i j Ert- i its -p / TENTATIVE TRACT MAP N0. 23935 AUGUST 1958 L :':.•6 :11:::4: •L2. 2C•st:T ■LS I2a�T:AL 1s.a 'J,�KI ]. rr:T-:O �u•2 ]!1: It 4GtL IM ::.[ acs l.tat:Ai sou .w ra:u: �esA r.t�lT ra:a ]:s7ltee tJGT it: r•rL1L1L :ll::A::2r 2t2:s:� tG[I Wrt: �Lr L1IAL 'L'n1CMl �rurr Wu 7r1rS[c.: r6L l2 .ALM SIO :2 /L .17amm to. y4D :1.ot stt•[M 2vLara. :Smrrat:a a r==Lu"j). 1t. 9 MS - is oututm �. "L: c. 17. 7213 •y :!T_C[3 _. :J1[ :. Icocw Y•1IR33tr :r'! ;CIF:. 17._ IL r6a266Ts 2w aus,Is, s i:. =Ts •a .. ,lAc3m Ot arSG.•I IaC 4A: 4'[1LtCL ]ISt7l:4. :L .w :Ea W -Tr '60 11302 C:1L 22 S.C! E wucc.61 q' to ZIL4-J 47 44 i6 :[SOI:• +:14a2IA 322" 16131 31.-41.5 112 1.-4 -r T2r S v4 wo 1[ 4G.730LLi no mm- 2r 7 . so ,:. 2r +. y • •. 2, Sst:.:a ! 3]12t2. -9 7 LAST, S" aLautt]:2c UsL Ami u:as:.+i vua: •.3tu 1 bllr]:-:Ol •I l.•11•><d 1 xy T-1 , etc. -- Indicates number and ' approximate location of exploratory trench P-1, etc. - Indicates number and approximate location of Percolation Test I {�f.•�.l _�r.�.�'{rl�� ENGINEERING SERVICE CORPORATION c08SULTARn W p.w L,u[o 04ANOISM � u- '�.i�i•rr«.- C 3Ln•e . :o'rrr�.�•. 1_12 Proj: Y91111'Y 9-O /Scale: lQed�ee4d oat e: /a - / - SS Engineer/Geologist: Drafting By. LEIGHTON AND ASSOCIATES, INC. I H I - „I VICINITY MAP NO SCALE 20 2Q p i TYPICAL SECTION - INTERIOR STREETS r SLY E ee' R/1. 26_ I EXISTOG ` PAVEUENT EM totasea W40 • i TYPICAL SECTION - MILES AVENUE W VT *, 4,r t E.W T TYPICAL SECTION - DUNE PALMS i j Ert- i its -p / TENTATIVE TRACT MAP N0. 23935 AUGUST 1958 L :':.•6 :11:::4: •L2. 2C•st:T ■LS I2a�T:AL 1s.a 'J,�KI ]. rr:T-:O �u•2 ]!1: It 4GtL IM ::.[ acs l.tat:Ai sou .w ra:u: �esA r.t�lT ra:a ]:s7ltee tJGT it: r•rL1L1L :ll::A::2r 2t2:s:� tG[I Wrt: �Lr L1IAL 'L'n1CMl �rurr Wu 7r1rS[c.: r6L l2 .ALM SIO :2 /L .17amm to. y4D :1.ot stt•[M 2vLara. :Smrrat:a a r==Lu"j). 1t. 9 MS - is oututm �. "L: c. 17. 7213 •y :!T_C[3 _. :J1[ :. Icocw Y•1IR33tr :r'! ;CIF:. 17._ IL r6a266Ts 2w aus,Is, s i:. =Ts •a .. ,lAc3m Ot arSG.•I IaC 4A: 4'[1LtCL ]ISt7l:4. :L .w :Ea W -Tr '60 11302 C:1L 22 S.C! E wucc.61 q' to ZIL4-J 47 44 i6 :[SOI:• +:14a2IA 322" 16131 31.-41.5 112 1.-4 -r T2r S v4 wo 1[ 4G.730LLi no mm- 2r 7 . so ,:. 2r +. y • •. 2, Sst:.:a ! 3]12t2. -9 7 LAST, S" aLautt]:2c UsL Ami u:as:.+i vua: •.3tu 1 bllr]:-:Ol •I l.•11•><d 1 xy T-1 , etc. -- Indicates number and ' approximate location of exploratory trench P-1, etc. - Indicates number and approximate location of Percolation Test I {�f.•�.l _�r.�.�'{rl�� ENGINEERING SERVICE CORPORATION c08SULTARn W p.w L,u[o 04ANOISM � u- '�.i�i•rr«.- C 3Ln•e . :o'rrr�.�•. 1_12 ENO, ,It . . . . . . . . . . . APPENDIX A SAMPLING AND TESTING PROCEDURES Samplinq Procedures Backhoe Trenches: Bulk samples were obtained from the trenches and returned to our laboratory for testing. In-place density and moisture tests were performed at original ground minus two feet and original ground minus four feet. In-place densities and moisture contents were determined in accordance with the sand cone method, ASTM 01556-64, and/or by the nuclear gauge, ASTM D2922-78. The ex- ploratory trenches were logged by our field representative concurrent with their excavation. Laboratory Testing Procedures Classification Tests: Typical materials were subjected to mechanical grain -size analysis by set sieving with U. S. Standard brass screens. The data was evaluated in determining the classification of the materials. A graphical presentation of the grain -size distribution is presented in the test data and the Unified Soil Classification is presented in both the test data and the Geotechnical Trench Logs. Maximum Density Tests: The maximum dry density and optimum moisture content of typical materials were determined in accordance with ASTM 01557-78. Sand Equivalents: The sand equivalents of typical samples were determined in accordance with A5TM D2419-74. fq Vii r• T,!!! TF44. •i w-d i CV•ti' �:- �. 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[ e �. . 4t W. •l � ' ,ti. � e 'f41. •'� �. • � ► � vu�[wti��I[Jy"}''e� ����r`��.'' ,w, •�"Af'`5' �;4� pr�,t'�' ��1�: t, . r �;: �•Y �.: w .I�- it 3 . nom% %�, t P Y'r "•y7! r'' S -OT.�•1�,14 ► Leer �. �� �' ire S• _tn • � �,t"a nys);f"�t` '� • y ��'YY-'.. � �(.s;};ti:�P.t.':r• c, yra '�i•-, ra k y,,x;:�. -757,7-jr.i+ M. ►a -^-h Mo:�� Da-i:e: l /�-8g aroject:LcL Dv,:n Y7 Job No: Equipment Type: Ford SSS Bach -toe— Equipment Company odde", 6"c}rL,a"2_ ovation: Ref. or Datum 9':5co 7' o a.3 5'- g Logged By: XJ[— .4 gp G +-' 2 v (n N E �O 4-- v� C v S- rp ul L u' i CJ °' � � coa C � +� C.1 �� to GEOTECHNICAL DESCRIPTION -0 GCJ r E c- 1.7 E C_ W +J GuA 4- >-,U 4A +-J — f r (i '-N G U- Z to G I-- F- C— i S'6.1k-( /s FE S �M Sdnd Se � �►r+d _C�A �i 9rA�+1 G� !.v r� (r` ^%a A *r Med, ❑,0,-A eF1-"'24d-"'24dO vP 44 ed, dnr► d2r7 sd; �V1d r� r �r . C ro 9 bedded Orr, ,,5 r o *4-446 4,c> /P " 41ep li /o3.b l./ MicQceo�.s LEIGHTON and ASSOCIATES, INC. beco•nc� vay s 1, yc,fy o,s-}' a+ 7' -+a) Dep+k : /o . A/o wee Gro,.nd wafo— E. -ed —%ru+ct, Sock-i71.r l 11-17-919 �� a7i 1 ti� j. •Y rich No:- -77-7- Oa -e: ! / 7-Sg 16 Project:LcL Oui�+�? 417 Job No: . /VZ/9-01 Equipment Type: Fo,-d SSS Bach -1 ce-- Equipment Company Oe3//,--Z evation: 76 ' Re`. or Datum 1�5co T o rte a39;S- 8� Logge'd By: �(,-- sP/srh 5�'�d S -Ili Sod -�:, e em'>%ed� mec),tM dense, ct�y, Jc�G/jMi�Qcic�s qg.7 1.1 «oss bedded, 9rasS roofle4-s -tv S" delsfi� �nQ.R �• S 0 GG v &/l 9 SQ Ste�e Sred Med,o;-i den il e�,,, 5 r.y�+y t 9miy /o 1.5 X LEIGHTON and ASSOCIATES, INC. 70--., Dep -i->„ : /a Alo trceQ Gra cid Wa4e,- Fico vr+wed —r,e4v In $a c k•Fi lied f- / 7- C T a E to.— V) s- a O Q) " ^ GEOTECHNICAL DcSCRIPTION +..i -0 G -W U4 -j w N a -J U C_C) r E E G GN TU •— C_ Gln G Q) cu L c— O O C sP/srh 5�'�d S -Ili Sod -�:, e em'>%ed� mec),tM dense, ct�y, Jc�G/jMi�Qcic�s qg.7 1.1 «oss bedded, 9rasS roofle4-s -tv S" delsfi� �nQ.R �• S 0 GG v &/l 9 SQ Ste�e Sred Med,o;-i den il e�,,, 5 r.y�+y t 9miy /o 1.5 X LEIGHTON and ASSOCIATES, INC. 70--., Dep -i->„ : /a Alo trceQ Gra cid Wa4e,- Fico vr+wed —r,e4v In $a c k•Fi lied f- / 7- C T Project:Lcv- Ovl;l 1w -h No: -7r-3 Date: I? j? y7 Job No: SSS /yy8 -ol Equipment Type: Ford SSS $ockG+oe— evation: 7Y Ref. or Datum r5<0 7,i4,-rroc-�t7apa�9;$- Eouipmelit Company_(Ja/Ie,� SlS$Logged By:-2L- y:DL41 d 41 r 2 v N Ln E ra tn O v s- +j ra "' S- a'cu o -� = a L + � "^ GEOTECHNICAL DESCRIPTION =- ci F_ G c- rn U — U v >> C ti to dr a 0 i G O O c C SOACJ� �f� $�: -�;/iG 9rC1��1Pd�/oosP mcd«M dcnsC� dr> , _ ��-� n�.�oc�ouS, Doss bpddcd a�1 � roof -1G - ion• 5 /. 8 Scildy r,%A at /O !S LEIGHTON and ASSOCIATES, INC. -7;;, a) Vep-fln : // " ;Vo free 6rourd 4/a4c- -15olcc-A 6-ect -1;--enck 13och4;Y/ed //-17-1?8 r Project:LcL Du,:n+c, '117 �nch No: Date Job No: Equipment Type: Ford SSS $oclfG.oe— Equipment Company Odde Back -toe vation: 6/� Ref. or Datum r5co Logged By: D6-- C- v E E ,n Q) rp roc L +j V' a o-- L u �-' �, GEOTtCHNICAL DESCRIPTION C.C7 r E E C C-0 �U � Cl Gln C: Q) > > iC Q' a QJ i G O O C C U- Z N G I--• F- M — M: (j �7 SP S�+d +,;4 qea, N ed, .wed.-+► deAse, 1077 .7. ( s l.3 L,+ly fi j i 4- sf,yc,f►/ .41eoCso., % :_I a I'°°.3 } 3.7 1 1 6GC',,n3 To +.a/ De poi, : 13 A!c Free Gra&,^d wo,-krF,.eo,4A+o-ed TrUct Sock -ailed 11-17- f er��h No: T- S Dake: !I • 7-Sg Project:LcL Ou,:n-fza _`/% Job No: -O ry8 I Equipment Type: �ord SSS $ocifL+oe-- Eouipmeot Company U611'ey -- - 70 ' Ref. or Datum C5co 7 �, o rim a39;S- S Logged By: +' a e of tL- �/+ a1 ra v- -+ o o y c, N GEOTECHNICAL DESCRIPTION +� J -c G 4-1 a) 4-j -� 4- CJ V) ++ r- V C_ Cl — E E G G V) >% U G a) O ,o ar a L c- O O c C U- L^ Z N i= F- F- C— i CJ N Q - !rte 15 ao SI% gond/s, 77,z_ stand - -G,e 9e-cn,;i ed, loo Se, to 8•S o: Q G4,f. 9�� s/.yG�y M,ccictov si cross bedded, 9r*s5 roofle-{-5 +o �, V lo7 �f f /. y CGL,�iA_q SP LEIGHTON and ASSOCIATES, INC. SQA e- aged, M eck z m de,75e, v�y a f j .v,oi3 i 9naX- 6row/1 70+&/ Pep fL:Ia' /1/o Fre e Gauw+d W a%Ei+ n o, n+e/r cf �1. Project:LaL Ovf;n+a `/7 �nch No:_777- /2_ Dace: Mbk/.7-1?9 Dob too: 5 88 /,/Y9 -Of Equipment Type: Ford SSS $ochf%noef- Eouipmelit Company vatinn 67� Rraf or D'tum r<co 7 J -r--4A4- x39;5- glqg Lovged By: �(�-- SP�SM Sct., d�� S� d = -�"r e 9 � r n ed rr rd..•.•►� ios. 3 0.7 dr..� s�� d��., �rra, % s �•� G ply ,•�,cac ro..5 c s s be-ddnd, To s�) r o n f /e-6 +z) / q 13 5 Laves is /0 ?o+a i Def,-rh , 13 S Alo Free Ground Wn�o�Fnto �fcrrCi ?rmch $ocirJr7/ed //-/7-99 FM I F:lrHTON and ASSOCIATES. INC r,'; G to E ea ra V' � o y DESCRI PT IOP! o C) V) V)GEOTECHNICAL �-+ +j 1 -0 G 4-a 1 O +.i � of 4-J U c- C) r E E G GLn U I •- a N U ci O O to a' T O L G O O C Z C LL Z Ln G F- F- C — z C-) LI SP�SM Sct., d�� S� d = -�"r e 9 � r n ed rr rd..•.•►� ios. 3 0.7 dr..� s�� d��., �rra, % s �•� G ply ,•�,cac ro..5 c s s be-ddnd, To s�) r o n f /e-6 +z) / q 13 5 Laves is /0 ?o+a i Def,-rh , 13 S Alo Free Ground Wn�o�Fnto �fcrrCi ?rmch $ocirJr7/ed //-/7-99 FM I F:lrHTON and ASSOCIATES. INC r,'; each No: --77-7 Date: Project:LcL c9u,:i '17 Job No: Equipment Tyoe: cord SSS $ockG'oe- _vation: 76 Ref. or Datum r5co -rrJ.Tro,.4 Eouipmel?t Company (Rckho& 12a3915- 5Z Logged By: CL v V1 E ro in 4- 41 ro .- s "' u O o -- = a " Z� GEOTECHNICAL DESCRIPTION +j _!. -c C_ CJ — E G E C- O +) t� c- V1 >1 U V1 +-+ U .r f- r In G w > > c to Q >1 4J L G O O C �- S r► Sand s; lf Said -rIA Z I ;141041 yro A.redl L --n dei+V, dry, 8ray; c1bs5 Io3.,Z p.5 bedded, M/Ooaeo�5 ! 3.�15 roof)e% -716 ia'�dcP+l� X03 y 9.0 S Guv��9 to M LEIGHTON and ASSOCIATES, INC. --ro+ai Dep+L, % 13, A% Free 6r0u.Ad W4+&— w�-rc�tCl 'TrQ'1G(n $ o c k-PlI ed //-/7-99 n c h No: Date: S17 -TO Project: LcL Ou ;ry a 7 Job No: Equipment Type: cord SSS Bach-l^oe— Equipment Company0611c-,,, B06Y ,Or, 4 R f or Dau t m FSco 7 t7 a39;S- 8 Logged By: 06— _vatinn. e e +.j a e LA t, E N aJ r0 v) s- (U 4- o C Qj L +••� = r- .- U-- GEOTECHINICAL DESCRIPTION _ W — o -- L Q, .0 C Y QJ +r 4- N 4-) r- U G CJ r E E G G N 7, u •r- C_ r- In C; cu rp Q a a) i G O O O C C LL C Z N C �- to �y 0.3 ti, ted[ dell Sei d�yr 5 M' Ca c e o L-- 5 c ro s 5 to e cI d,4 d. 9M S S ro o f I -e 4--,..4-o /d" dere bN 911 q a.o /0 i cir_u rnki -n.,e4 e ccnrl eTF.q stir --rc4wl DePfl,:la• Y. Fri GDvrd !'<,4a4ci 97ncovn+evd -rienGk $ar-k-Fi7%Pd //-/7-1?8 Jnr h No: T 9 Dake: 7 -SS 'Project: LeL Ov,:nfa 617 Job No: Equipment Type: Ford rSS Bach -ice- Equipment Company (JC11e c}rh❑ evaZ�on: LEIGHTON and ASSOCIATES, INC. on Ret, or uatum F-sca 7f4.Trncf,,4e_j2c�J'/;5 - � Wuoggeo by: U&- C •r �. v V1 s E "' c °' ° in o-- .N N rp c "�, GEOTECHNICAL DESCRIPTION G CJ E F G G N >1 u — r_ Vl U ci CU- O 7 CZ rp Qr V1p >-, cu L c— O O c C (i�tk 1 sP/�„I $and�Sand' -4;r+e 9m-;necl, �eeidryer 5r¢lr v trx M.'Caido0 � /05.0 / / [r❑ 5 bedded, 9rn, s s rvo+le fs -(o y`,,00At; 96• L �• 8 sb91,4 MiGG4 a"5 hero,., ef41, S Sarna c 9 ,;,ted, �ed��%+•, deyj gnax /O No Fr -re K-0 ur+d W a +6--- / iJ -re-mcln $ackCi led //^/%- a D LEIGHTON and ASSOCIATES, INC. Project:/ -ex 6)u,✓i 1 nch No: - /p Dates - x1 7 atesy7 Job No: SS88 /'/`i8 -01 Equipment Type: For-rl SSS $oc-lflnoef- Eouipmelit Cc^:gany oo/%,� ch vaiinn:_ 6y Ref. or Datum rSco -r !, a ,o4 ag d39;5- 8 LoCced Ey: )]C CL r VI E 1n co 4- c _ LO L a, _ o c> > c �^ GEOTECHII:CAL DrESCRIPTI0i1 W— � G ^ t C) In -0 % Lj CU i.! 4- Vl +d V F Gl >> M d, T cu i G O O c CZ ul= Com... U f") SP/S�Sancl/S: I Sid -E;;1e 9rr,� ed, loose lo2a a6 d'y� Sr°yi «o5s bedded sG9a41 -I M�c4cPo�S I'grts5 /os.o 0.0 der-/ L, 5 n Iro4oi pcp-t& : /a No Free- G•ound Ene-o AA+e,-ccl �5 Tregct,, Back{ --//ed 11 -17 -VT q. md fir. E4� 9:00 Depth of 3'deP�G, -1v Cf Ir_ pole: pF/ 6e4�o/i Test Hole No.: �' � T a Date Excavated: _ /%'/ 7 g Final Soil Classification: Check for Sandy Soil Criteria Tested By: Presoak: Date: //- Actual hk Percolation Tested By: Time Level Date:// -.73- Level Rate Time (min.) (min.) SAIVD'f SCIL CRITERIA TE.:: (inches) (inches) (min./inch) Time Initial Final A ir. Trial /O. o Interval Water Level Water Level Water Level No. Time (min.) (inches) (inches) (inches) { g'.ou— O 9"'/o -/0.0 60 /O.O 1 /o. o 0.7 Q-, ;:5 g� I �? O - /D.D /O.o 2 _1 J � � 9:00 Use Normal Sandy (Circle One) Soil Criteria ao 0-/0.0 Total Initial Final A in Time Elapsed Water Water Water Percolation Interval Time Level Level Level Rate Time (min.) (min.) (inches) (inches) (inches) (min./inch) -/ o. o /0.0 0.7 /o O -/o. o /O. o D S 9:00 0/ ao 0-/0.0 /0. o Q. �o 7 30 O -/o. o /o. o O. 7 q:aa 9•0?0 7 yo 0 -/ o. o /0.0 0.7 5.30 � y { 9"'/o 7 60 O -/o. o /o. o 0.7 9:So Project No. _ PERCOLATION DATA SHEET Project Name -4p, O�..+�a '�'7 ID FOR LEACH LINE Date / • 3• I?g Figure No. 3060 708 1 Test - Hole No.:2—A", � --7 Depth of •t Hole: of Date Excavated: - Sf( Soil Classification: Sp/$.- --- Trial No. Check for Sandy Soil Criteria Tested By: Date: 1I -?3 -?Ir Actual Percolation Tested By: EL Date: Trial No. Time Time Interval (min.) SAITOY SOIL. CRITERIA TES i Initial Fir.'_ Water Level Water Level (inches) (inches) G i:: Water Level (inches) O' ;24 D /0-0 i I // a /o. o I Time Time Interval (min.) Use Normal Sandy (Circle One) Soil Criteria Total Initial Final A in Elapsed Water Water Water Time Level Level Level (min.) (inches) (inches) (inches) Percolation Rate (min./inch) O /i=a5 5 -3o C> moo. o 10-0 D• S 1L•3ri O –/ O. O /O.O �• S 60 O -/o. o /0.0 O.S 0 PERCOLATION DATA SHEET FOR LEACH LINE Project No. Project Name to a,:4a y7 O Date 88 Figure No. 3060 788 Al V •;: '"�:; - •'.L'••3 ifi' LTJ �r:'ti+c'-'.. iX ❑ - �- a' _ :� ��:`4L :-y:;::: PEND 1`; •� _ {'`r3�•�l� :,�:..1w r� aiF �.i'I ��1 ..1f•tl'.•` _ _ .4• •' •ori•• 1}p" i •iYf� �r R ,[�.Ir''?Ei�••;.�• ; b,•r• .;. 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LEIGHTON AND ASSOCIATES 5881448-01 Sa le Location T-3, Bulk -1 @ 2-3' MAXIMUM DENSITY TEST RESULTS * Soil Description Sand/Silty Sand: fine grained, gray; micaceous * In accordance with ASTM D1557-78. Sample Location T-1, Bulk -1 @ 4-5' T-3, Bulk -1 @ 2-3' T-9, Bulk -1 @ 0-2' Optimum Moisture % 11.0 SAND EQUIVALENT TEST RESULTS** Soil Descriotion Sand/Silty Sand: fine grained, gray; micaceous Sand/Silty Sand: fine grained, gray; micaceous Sand/Silty Sand: fine grained, gray; very micaceous **In accordance with ASTM D2419-74. Maximum Dry Density (pcf ) 116.0 Sand Equivalent 61 49 58 D -i - g m m U � Ov r�.i 0 Q C C 2 n N ma as ao v�n N n ad Z UCh Q 1 O Oi• Lm r- w A IT Percent Finer by Weight Project No.. 5881448-01 ]In• Ilniu. I nimhtnn A A-,gnriatAS ®o &0 a V c Note No.: D-11 U � N C C 2 n N ma as ao v�n N n ad Z UCh Q 1 O C*d 0 Q 0_ a o i 11I Il I44 J: I ! J 0 O M 7 ^ � O10 I I U� ° W O 0 oz° Cn • 0 0 E O Cn Note No.: D-11 LEIGHTON AND ASSOCIATES GENERAL EARTHWORK AND GRADING SPECIFICATIONS 0- 1.0 General Intent These specifications present general procedures and requirements for grading and earthwork as shown on the approved grading plans, including preparation of areas to be filled, placement of fill, installation of subdrains, and excavations. The recommendations contained in the geotechnical report are a part of the earthwork and grading specifications and shall supersede the provi- sions contained hereinafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these specifications or the recommendations of the geotechnical report. 2.0 Earthwork Observation and Testina Prior to the commencement of grading, a qualified geotechnical consultant (soils engineer and engineering geologist, and their representatives) shall be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report and these specifications. It will be necessary that the consultant provide ade- quate testing and observation so that he may determine that the work was accomplished as specified. It shall be the responsibility of the contractor to assist the consultant and keep him apprised of work schedules and changes so that he may schedule his personnel accordingly. • It shall be the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the work in accordance with applicable grading codes or agency ordinances, these specifications and the approved grading plans. If, in the opinion of the consultant, unsatisfactory condi- tions, such as questionable soil, poor moisture condition, inadequate compaction, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the consultant will be empowered to reject the work and recommend that construction be stopped until the conditions are rectified. Maximum dry density tests used to determine the degree of compaction will be performed in accordance with the American Society for Testing and Materials test method ASTM D1557-78. 3.0 Preparation of Areas to be Filled 3.1 Clearing and Grubbing: All brush, vegetation and debris shall be removed or piled and otherwise disposed of. 3.2 Processing: The existing ground which is determined to be satisfactory for support of f 11 shall be scarified to a minimum depth of 6 inches. Existing ground which is not satisfactory shall be overexcavated as specified in the following section. Scarification shall continue until • the soils are broken down and free of large clay lumps or clods and until the working surface is reasonably uniform and free of uneven features which would inhibit uniform compaction. 3.3 Overexcavation: Soft, dry, spongy, highly fractured or otherwise un- suitable grouna, extending to such a depth that surface processing cannot • adequately improve the condition, shall be overexcavated down to firm ground, approved by the consultant. 4.0 • 0 3.4 Moisture Conditioning: Overexcavated and processed soils shall be watered, dried -back, blended, and/or mixed, as required to attain a uniform moisture content near optimum. 3.5 Recompaction: Overexcavated and processed soils which have been properly mixed and moisture -conditioned shall be recompacted to a minimum relative compaction of 90 percent. 3.6 Benchino: Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. The lowest bench shall be a minimum of 15 feet wide, shall be at least 2 feet deep, shall expose firm material, and shall be approved by the consultant. Other benches shall be excavated in firm material for a minimum width of 4 feet. Ground sloping flatter than 5:1 shall be benched or otherwise overexcavated when considered necessary.by the consultant. 3.7 Approval: All areas to receive fill, including processed areas, removal areas and toe -of -fill benches shall be approved by the consultant prior to fill placement. Fill Material 4.1 General: Material to be placed as fill shall be free of organic matter and other deleterious substances, and shall be approved by the consultant. Soils of poor gradation, expansion, or strength characteristics shall be placed in areas designated by the consultant or shall be mixed with other soils to serve as satisfactory fill material. 4.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 12 inches, shall not be buried or placed in fills, unless the location, materials, and disposal methods are specifically approved by the consultant. Oversize disposal operations shall be such that nesting of oversize material does not occur, and such that the oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 feet vertically of finish grade or within the range of future utilities or underground construction, unless specifically approved by the consultant. 4.3 Import: If importing of fill material is required for grading, the import material shall meet the requirements of Section 4.1. n '5.0 Fill Placement and Compaction 5.1 Fill Lifts: Approved fill material shall be placed in areas prepared to • receive fill in near -horizontal layers not exceeding 6 inches in compacted thickness. The consultant may approve thicker lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to attain uniformity of material and moisture in each layer. 5.2 Fill Moisture: Fill layers at a moisture content less than optimum shall be watered and mixed, and wet fill layers shall be aerated by scarifica- tion or shall be blended with drier material. Moisture -conditioning and mixing of fill layers shall continue until the fill material is at a uniform moisture content at or near optimum. 5.3 Compaction of Fill: After each layer has been evenly spread, moisture conditioned, and mixed, it shall be uniformly compacted to not less than 90 percent of maximum dry density. Compaction equipment shall be ade- quately sized and shall be either specifically designed for soil compaction or of proven reliability, to efficiently achieve the specified degree of compaction. 5.4 Fill Slopes: Compacting of slopes shall be accomplished, in addition to normal compacting procedures, by backrolling of slopes with sheepsf oot rollers at frequent increments of 2 to 3 feet in fill elevation gain, or by other methods producing satisfactory results. At the completion of grading, the relative compaction of the slope out to the slope face shall be at least 90 percent. 5.5 Compaction Testing: Field tests to check the fill moisture and degree of compaction will be performed by the consultant. The location and fre- quency of tests shall be at the consultant's discretion. In general, the tests will be taken at an interval not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of embankment. In addition, on slope faces, at least one test shall be taken for each 5,000 square feet of slope face and/or each 10 feet of vertical height of slope. 6.0 Subdrain Installation Subdrain systems, if required, shall be installed in approved ground to conform to the approximate alignment and details shown on the plans or herein. The subdrain location or materials shall not be changed or modified without the approval of the consultant. The consultant, however, may recommend and upon approval, direct changes in subdrain line, grade or material. All subdrains should be surveyed for line and grade after installation and sufficient time shall be allowed for the surveys, prior to commencement of filling over the subdrains. • 7.0 Excavation • Excavations and cut slopes will be examined during grading. If directed by the •consultant, further excavation or overexcavation and refilling of cut areas shall he performed, and/or remedial grading of cut slopes shall be performed. 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F' .}". rS 1 s� R 6 .'1 k -r r AMAka ASSOC TES ;� 5881448-01 REFERENCES County of Riverside and Envicom Corporation, Seismic Safety and Safety General Plan Elements, Technical Report, Volumes I and II, dated September, 1976. Leighton and Associates, 1987, "Geotechnical Investigation for Proposed General Telephone Building, Located 1/4 Mile South of Miles Avenue, East of Dune Palms Road, Indio, California", report dated February 2, 1987, Project No. 5870003-01.